Effect of varying chain length between P1 and P1′ position of tripeptidomimics on activity of angiotensin-converting enzyme inhibitors

One of the efficient modes of treatments of chronic hypertension and cardiovascular disorders has been to restrain the formation of angiotensin-II by inhibiting the action of angiotensin-converting enzyme (ACE) on angiotensin-I. The efforts continue towards achieving superior molecules or drugs with improved affinities, better bioavailability and thus to achieve long duration of action with minimum side effects. Previously, we reported a library of tripeptidomimics of Ornithyl–Proline (Orn–Pro) conjugated with various unnatural amino acids and carboxylic acid derived heterocyclics based on the SAR studies of existing ACE inhibitors. Their synthesis and screening for possible inhibitors of angiotensin-converting enzyme (ACE) revealed that increase in the backbone chain length by one carbon atom results in a sudden decrease in their activity. Therefore, in the present study heterocycles with different chain length were introduced to interact with the hydrophobic S₂ sub-site of ACE and screened for their in vitro ACE inhibition activity. Further, their binding interaction with C-domain of somatic ACE was also determined. Docking and consequent LUDI scores showed good correlation with binding of these molecules in the active site of ACE. Results suggest that heterocycles with C₃ chain length are more appropriate for the effective binding of the tripeptidomimics within the active site of ACE.     

A sorghum 85 kDa heat stress-modulated protein shows calmodulin-binding properties and cross-reactivity to anti-Neurospora crassa Hsp 80 antibodies

The present study, carried out to identify stress-modulated calmodulin (CaM)-binding proteins in sorghum, resulted in the isolation of several proteins, which showed binding to CaM-Sepharose matrix. Calmodulin gel overlay assay and MALDI-ToF MS analysis revealed that an 85 kDa protein (Hsp85), which interacted with calmodulin, cross-reacted with anti-N. crassa Hsp80 antibodies. Since these antibodies bind to plant Hsp90, sorghum Hsp85 is likely to be a member of the Hsp90 family. This study provides the first evidence that a member of Hsp90 (Hsp85) in plants exhibits CaM-binding properties.     

Does fish represent an intermediate stage in the evolution of ureotelic cytosolic arginase I?

Arginase catalyses the last step of the urea cycle. At least two isoenzymes of arginase are known; cytosolic ARG I and mitochondrial ARG II. ARG I is predominantly expressed in liver cytosol, as a part of urea cycle in ureotelic animals. The second isoform ARG II is primarily responsible for non-ureogenic functions, expressed in mitochondria of both hepatic and non-hepatic tissues in most vertebrates. Most micro-organisms and invertebrates are known to have only one type of arginase, whose function is unrelated to ornithine-urea cycle (OUC). However, in ureo-osmotic marine elasmobranchs arginase is localized in liver mitochondria as a part of OUC to synthesize urea for osmoregulation. An evolutionary transition occurred in arginase enzyme in terrestrial ureotelic vertebrates, with the evolution of ARG I from a pre-existing ancestral mitochondrial ARG II. This cytosolic ARG I activity is supposed to have first appeared in lung fishes, but the 40% and 60% distribution of arginase I and II activity in liver and kidney tissue of Heteropneustes fossilis indicates reconsideration of the above fact.     

Production and biochemical characterization of a novel cellulase-poor alkali-thermo-tolerant xylanase from <Emphasis Type="Italic">Coprinellus disseminatus</Emphasis> SW-1 NTCC 1165

Fungi producing xylanases are plentiful but alkali-thermo-tolerant fungi producing cellulase-poor xylanase are rare. Out of 12 fungal strains isolated from various sources, Coprinellus disseminatus SW-1 NTCC 1165 yielded the highest xylanase activity (362.1 IU/ml) with minimal cellulase contamination (0.64 IU/ml). The solid state fermentation was more effective yielding 88.59% higher xylanase activity than that of submerged fermentation. An incubation period of 7 days at 37°C and pH 6.4 accelerated the xylanase production up to the maximum level. Among various inexpensive agro-residues used as carbon source, wheat bran induced the maximum xylanase titres (469.45 IU/ml) while soya bean meal was the best nitrogen source (478.5 IU/ml). A solid substrate to moisture content ratio of 1:3 was suitable for xylanase production while xylanase titre was repressed with the addition of glucose and lactose. The xylanase and laccase activities under optimized conditions were 499.60 and 25.5 IU/ml, respectively along with negligible cellulase contamination (0.86 IU/ml). Biochemical characterization revealed that optimal xylanase activity was observed at pH 6.4 and temperature 55°C and xylanase is active up to pH 9 (40.33 IU/ml) and temperature 85°C (48.81 IU/ml). SDS–PAGE and zymogram analysis indicated that molecular weight of alkali-thermo-tolerant xylanase produced by C. disseminatus SW-1 NTCC 1165 was 43 kDa.     

A conceptual framework to analyse the land-use/land-cover changes and its impact on phytodiversity: a case study of North Andaman Islands,India

Phytodiversity is affected both by natural and anthropogenic factors and in Island ecosystems these impacts can devastate or reduce diversity, if the native vegetation is lost. In addition to rich species richness and diversity, Island systems are the sites of high endemism and any threat to these ecosystems will consequently lead to loss and extinction of species. To understand the dynamics including feedbacks of these changes in phytodiversity of North Andaman Islands, a conceptual framework is proposed which focuses on understanding the land-use and land-cover changes and its impact with phytodiversity. In considering land-use and land-cover changes this work highlights the direct and indirect drivers of changes—socio-economic, biophysical and climatic factors. Migration of population, their socio economic needs and government policies were identified as major driving forces threatening the phytodiversity of these Islands. Apart from human beings, natural disasters like tsunami and introduced herbivorous animals like elephants also contributed to forest destruction in these Islands. The integrated analysis based on such framework will provide insights for holistic resource management including ecological conservation.     

Characterization of 1,3-regiospecific lipases from new Pseudomonas and Bacillus isolates

Lipase producing ability of 120 bacterial isolates was examined qualitatively, resulting in 32 lipase producers, which were further screened for 1,3-regiospecificity. Three Bacillus (GK-8, GK-31 and GK-42) and one Pseudomonas (GK-80) were found to produce 1,3-regiospecific lipases. These lipases were alkaline in nature as they showed pH optima of 9.0 and high stability in the alkaline pH range of 8.0–11.0. The lipases from three Bacillus isolates, viz. GK-8, GK-31 and GK-42 showed temperature optima of 37 °C, whereas the Pseudomonas (GK-80) lipase showed optimum activity at 50 °C. The lipase of GK-8 was highly stable and showed enhanced activity in different organic solvents like petroleum ether (172%), diethyl ether (143%) and acetone (135%).     

Human retinal and brain cell lines: A model of HCMV retinitis and encephalitis

Although HIV is accepted as the etiologic agent in AIDS, other factors have been implicated in accelerating the disease. Human cytomegalovirus (HCMV) in particular has been implicated as a cofactor in the progression from AIDS-related complex (ARC) to AIDS. HCMV infection of the central nervous system (CNS) (brain, retina) has been reported in at least 50% of AIDS patients, and has been implicated in producing encephalitis and sight-threatening retinitis. HCMV exhibits strict species specificity and animal models for human HCMV are conspicuous by their absence. We have developed a human brain cell line (mixed glial/neuronal) and a multipotential human retinal precursor cell line (neuronal in nature). We have tested the suitability of these cell lines as models for the study of HCMV infectibility. In this study, we report that these cell lines are optimal for the study of HCMV infectibility and pathogenesis in tissues of neural origin and appropriate to study HIV-HCMV interaction. Immortalized human brain and retinal cell lines were infected with a laboratory strain of HCMV (AD 169, Towne) at a multiplicity of infection moi (1-5) and viral infectibility and cell specificity monitored by: (a) phenotypic analysis (multinucleate cells, syncytium formation, etc.), (b) antigen expression (IE, E, late) by immunohistochemistry, Western blot analysis, (c) presence of viral particles by TEM, and (d) expression of indicator plasmids (HIV-LTR-CAT). We report that both human retinal and brain cell lines are permissive for HCMV infectibility. Cell specificity was not seen; both cells expressing glial/neuronal cell markers were positive for the presence of HCMV early/late antigens. Formation of multinucleate giant cells with nuclear inclusion bodies and syncytia were seen. Productive viral infection was confirmed by the ability of cell-free supernatant from the third passage of infected cells to produce pathogenicity and express viral particles, when added to fresh cultures. Using indicator plasmids, HIV-LTR, and CAT, we have shown that HIV and HCMV interact at the cellular level. We have also shown that HIV production in retinal and brain cell lines transfected with cloned HIV was enhanced by HCMV-IE genes. We did not see any differences in HCMV. AD 169, Towne isolate, and data from both strains is presented in this paper. This model could prove extremely useful for the study of cell specificity/cellular and molecular interaction between HIV/HCMV and to test antiviral therapies.     

Complexity of gas vesicle biogenesis in Halobacterium sp. strain NRC-1: identification of five new proteins

The genome of Halobacterium sp. strain NRC-1 contains a large gene cluster, gvpMLKJIHGFEDACNO, that is both necessary and sufficient for the production of buoyant gas-filled vesicles. Due to the resistance of gas vesicles to solubilization, only the major gas vesicle protein GvpA and a single minor protein, GvpC, were previously detected. Here, we used immunoblotting analysis to probe for the presence of gas vesicle proteins corresponding to five additional gvp gene products. Polyclonal antisera were raised in rabbits against LacZ-GvpF, -GvpJ, and -GvpM fusion proteins and against synthetic 15-amino-acid peptides from GvpG and -L. Immunoblotting analysis was performed on cell lysates of wild-type Halobacterium sp. strain NRC-1, gas vesicle-deficient mutants, and purified gas vesicles, after purification of LacZ fusion antibodies on protein A and beta-galactosidase affinity columns. Our results show the presence of five new gas vesicle proteins (GvpF, GvpG, GvpJ, GvpL, and GvpM), bringing the total number of proteins identified in the organelles to seven. Two of the new gas vesicle proteins are similar to GvpA (GvpJ and GvpM), and two proteins contain predicted coiled-coil domains (GvpF and GvpL). GvpL exhibited a multiplet ladder on sodium dodecyl sulfate-polyacrylamide gels indicative of oligomerization and self-assembly. We discuss the possible functions of the newly discovered gas vesicle proteins in biogenesis of these unique prokaryotic flotation organelles.     

Density-dependent differentiation in nontransformed human retinal progenitor cells in response to basic fibroblast growth factor- and transforming growth factor-alpha

Multipotential retinal precursors give rise to all cell types seen in multilayered retina. The generation of differentiation and diversity of neuronal cell types is determined by both extrinsic regulatory signals and endogenous genetic programs. We have previously reported that cell commitment in human retinal precursor cells (SV-40T) can be modified in response to exogenous growth factors, basic fibroblast growth factor, and transforming growth factor alpha (bFGF and TGFalpha). We report in this study that nontransformed human retinal precursors differentiate into photoreceptors by a cell density-dependent mechanism, and the effects were potentiated by bFGF and TGFalpha alone or in combination. A larger proportion of multipotential precursors plated at a density of 1 x 10(4) cells/cm(2) differentiated into neurons (photoreceptors) compared to cells plated at 3-5 x 10(4)/cm(2) and 1 x 10(5) cells/cm(2) under serum-free conditions and the effects were amplified seven- to eightfold in response to growth factors. Basic fibroblast growth factor (bFGF) and TGFalpha can induce 90% of the cells to assume a photoreceptor phenotype at a lower cell density, compared to only 30 and 25% of the cells acquiring a photoreceptor phenotype at intermediate and higher cell densities. Furthermore, at a lower cell density, 60-70% of the cells incorporate Bromodeoxyuridine (Brdu), suggesting that cells in a cell cycle may make a commitment to a specific fate in response to neurotrophins. Neurons with a photoreceptor phenotype were positive for three different sets of antibodies for rods/cones. Cells also exhibited upregulation of other proteins such as a D4 receptor protein expressed in photoreceptors, protein kinase Calpha (PKCalpha) expressed in rod bipolars and blue cones, and some other neuronal cell types. This was also confirmed by Western blot analysis. Newly derived photoreceptors survive for a few days before significant cell death ensues under serum-free conditions. To summarize, differentiation in precursors is density dependent, and growth factors amplify the effects.     

Fungistatic activity of Semecarpus anacardium Linn. f nut extract

Alcoholic extract of dry nuts of S. anacardium showed dose dependent antifungal activity in vitro against Aspergillus fumigatus and Candida albicans. At 400 mg/ml concentration, growth of both the fungi was inhibited and considerable reduction in size of cells and hyphae was observed. Sporulation also decreased.